Abstract:

A multi-band monopole antenna for a mobile communications device includes
a common conductor coupled to both a first radiating arm and a second
radiating arm. The common conductor includes a feeding port for coupling
the antenna to communications circuitry in a mobile communications
device. In one embodiment, the first radiating arm includes a
space-filling curve. In another embodiment, the first radiating arm
includes a meandering section extending from the common conductor in a
first direction and a contiguous extended section extending from the
meandering section in a second direction.

Claims:

1. A clamshell-type multi-band mobile communications device comprising:an
upper circuit board;a lower circuit board comprising a ground plane, a
feeding point, and communications circuitry, the feeding point being
coupled to the communications circuitry;a multi-band antenna coupled to
the communications circuitry and mounted on the lower circuit board, the
multi-band antenna comprising:a common conductor coupled to the feeding
point;a first radiating arm coupled to the common conductor;a second
radiating arm coupled to the common conductor;an upper housing and a
lower housing connected by a hinge, the upper housing enclosing the upper
circuit board and the lower housing enclosing the lower circuit board,
the hinge enabling the housings and the circuit boards to be folded
together into a clamshell configuration and opened into a communications
configuration; andwherein the hinge enables the lower circuit board to be
electrically coupled to the upper circuit board.

2. The clamshell-type multi-band mobile communications device of claim 1,
wherein the multi-band antenna is mounted on the lower circuit board
adjacent to the hinge.

3. The clamshell-type multi-band mobile communications device of claim 1,
wherein a projection of a footprint of the multi-band antenna on a plane
of the lower circuit board intersects a metallization of the ground plane
by not more than fifty percent.

4. The clamshell-type multi-band mobile communications device of claim 1,
wherein the multi-band antenna is laterally offset from an edge of the
ground plane.

5. The clamshell-type multi-band mobile communications device of claim 1,
wherein the total length of the first radiating arm is selected to tune
the first radiating arm to a first frequency band and the total length of
the second radiating arm is selected to tune the second radiating arm to
a second frequency band.

6. The clamshell-type multi-band mobile communications device of claim 5,
wherein the multi-band antenna is mounted on the lower circuit board
adjacent to the hinge.

7. The clamshell-type multi-band mobile communications device of claim 5,
wherein a projection of a footprint of the multi-band antenna on a plane
of the lower circuit board intersects the ground plane by not more than
fifty percent.

8. The clamshell-type multi-band mobile communications device of claim 5,
wherein the multi-band antenna is laterally offset from an edge of the
ground plane.

9. The clamshell-type multi-band mobile communications device of claim 1,
wherein the first radiating arm and the second radiating arm are
substantially coplanar.

10. A clamshell-type multi-band mobile communications device comprising:an
upper circuit board;a lower circuit board comprising a ground plane, a
feeding point, and communications circuitry, the feeding point being
coupled to the communications circuitry;a multi-band antenna coupled to
the communications circuitry and mounted on the lower circuit board, the
multi-band antenna comprising:a common conductor coupled to the feeding
point;a first radiating arm coupled to the common conductor;a second
radiating arm coupled to the common conductor;an upper housing and a
lower housing connected by a hinge, the upper housing enclosing the upper
circuit board and the lower housing enclosing the lower circuit board,
the hinge enabling the housings and the circuit boards to be folded
together into a clamshell configuration and opened into a communications
configuration;wherein the hinge enables the lower circuit board to be
electrically coupled to the upper circuit board; andwherein the first
radiating arm has a meandering section extending from the common
conductor in a first direction and a substantially-straight section
contiguous with the meandering section in a second substantially-opposite
direction as the meandering section.

11. The clamshell-type multi-band mobile communications device of claim
10, wherein the multi-band antenna is mounted on the lower circuit board
adjacent to the hinge.

12. The clamshell-type multi-band mobile communications device of claim
10, wherein a projection of a footprint of the multi-band antenna on a
plane of the lower circuit board intersects the ground plane by not more
than fifty percent.

13. The clamshell-type multi-band mobile communications device of claim
10, wherein the multi-band antenna is laterally offset from an edge of
the ground plane.

14. The clamshell-type multi-band mobile communications device of claim
10, wherein the total length of the first radiating arm is selected to
tune the first radiating arm to a first frequency band and the total
length of the second radiating arm is selected to tune the second
radiating arm to a second frequency band.

16. The clamshell-type multi-band mobile communications device of claim
14, wherein a projection of a footprint of the multi-band antenna on a
plane of the lower circuit board intersects the ground plane by not more
than fifty percent.

17. The clamshell-type multi-band mobile communications device of claim
14, wherein the multi-band antenna is laterally offset from an edge of
the ground plane.

18. The clamshell-type multi-band mobile communications device of claim
10, wherein the first radiating arm and the second radiating arm are
substantially coplanar.

19. A clamshell-type multi-band mobile communications device comprising:an
upper circuit board;a lower circuit board comprising a ground plane, a
feeding point, and communications circuitry, the feeding point being
coupled to the communications circuitry;a multi-band antenna coupled to
the communications circuitry and mounted on the lower circuit board, the
multi-band antenna comprising:a common conductor coupled to the feeding
point;a first radiating arm coupled to the common conductor;a second
radiating arm coupled to the common conductor;an upper housing and a
lower housing connected by a hinge, the upper housing enclosing the upper
circuit board and the lower housing enclosing the lower circuit board,
the hinge enabling the housings and the circuit boards to be folded
together into a clamshell configuration and opened into a communications
configuration;wherein the hinge enables the lower circuit board to be
electrically coupled to the upper circuit board; andwherein the first
radiating arm comprises a space-filling curve extending from the common
conductor in a first direction and a contiguous extended
substantially-straight section extending from the meandering section in a
second direction, the contiguous extended substantially-straight section
extending in a substantially-opposite direction as the meandering
section.

20. The clamshell-type multi-band mobile communications device of claim
19, wherein the multi-band antenna is mounted on the lower circuit board
adjacent to the hinge.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This patent application is a continuation application of, and
incorporates by reference the entire disclosure of, U.S. patent
application Ser. No. 12/055,748, which was filed on Mar. 26, 2008. U.S.
patent application Ser. No. 12/055,748 is a continuation application of
U.S. Pat. No. 7,403,164, issued on Jul. 22, 2008. U.S. Pat. No. 7,403,164
is a continuation application of U.S. Pat. No. 7,411,556, issued on Aug.
12, 2008. U.S. Pat. No. 7,411,556 is a continuation application of
International Patent Application No. PCT/EP02/14706, filed on Dec. 22,
2002. This patent application incorporates U.S. patent application Ser.
No. 12/055,748, U.S. Pat. No. 7,403,164, U.S. Pat. No. 7,411,556, and
International Patent Application No. PCT/EP02/14706 by reference.

BACKGROUND OF THE INVENTION

[0002]1. Technical Field of the Invention

[0003]This invention relates generally to the field of multi-band monopole
antennas. More specifically, a multi-band monopole antenna is provided
that is particularly well-suited for use in mobile communications
devices, such as Personal Digital Assistants, cellular telephones, and
pagers.

[0004]2. Description of Related Art

[0005]Multi-band antenna structures for use in a mobile communications
device are known in this art. For example, one type of antenna structure
that is commonly utilized as an internally-mounted antenna for a mobile
communication device is known as an "inverted-F" antenna. When mounted
inside a mobile communications device, an antenna is often subject to
problematic amounts of electromagnetic interference from other metallic
objects within the mobile communications device, particularly from the
ground plane. An inverted-F antenna has been shown to perform adequately
as an internally mounted antenna, compared to other known antenna
structures. Inverted-F antennas, however, are typically
bandwidth-limited, and thus may not be well suited for bandwidth
intensive applications.

SUMMARY OF THE INVENTION

[0006]A multi-band monopole antenna for a mobile communications device
includes a common conductor coupled to both a first radiating arm and a
second radiating arm. The common conductor includes a feeding port for
coupling the antenna to communications circuitry in a mobile
communications device. In one embodiment, the first radiating arm
includes a space-filling curve. In another embodiment, the first
radiating arm includes a meandering section extending from the common
conductor in a first direction and a contiguous extended section
extending from the meandering section in a second direction.

[0007]A mobile communications device having a multi-band monopole antenna
includes a circuit board, communications circuitry, and the multi-band
monopole antenna. The circuit board includes an antenna feeding point and
a ground plane. The communications circuitry is coupled to the antenna
feeding point of the circuit board. The multi-band monopole antenna
includes a common conductor, a first radiating arm and a second radiating
arm. The common conductor includes a feeding port that is coupled to the
antenna feeding point of the circuit board. The first radiating arm is
coupled to the common conductor and includes a space-filling curve. The
second radiating arm is coupled to the common conductor. In one
embodiment, the circuit board is mounted in a first plane within the
mobile communications device and the multi-band monopole antenna is
mounted in a second plane within the mobile communications device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a top view of an exemplary multi-band monopole antenna for
a mobile communications device;

[0009]FIG. 2 is a top view of an exemplary multi-band monopole antenna
including one alternative space-filling geometry;

[0013]FIG. 12 is an exploded view of an exemplary clamshell-type cellular
telephone having a multi-band monopole antenna;

[0014]FIG. 13 is an exploded view of an exemplary candy-bar-style cellular
telephone having a multi-band monopole antenna; and

[0015]FIG. 14 is an exploded view of an exemplary personal digital
assistant (PDA) having a multi-band monopole antenna.

DETAILED DESCRIPTION OF THE DRAWINGS

[0016]Referring now to the drawing figures, FIG. 1 is a top view of an
exemplary multi-band monopole antenna 10 for a mobile communications
device. The multi-band monopole antenna 10 includes a first radiating arm
12 and a second radiating arm 14 that are both coupled to a feeding port
17 through a common conductor 16. The antenna 10 also includes a
substrate material 18 on which the antenna structure 12, 14, 16 is
fabricated, such as a dielectric substrate, a flex-film substrate, or
some other type of suitable substrate material. The antenna structure 12,
14, 16 is preferably patterned from a conductive material, such as a
metallic thick-film paste that is printed and cured on the substrate
material 18, but may alternatively be fabricated using other known
fabrication techniques.

[0017]The first radiating arm 12 includes a meandering section 20 and an
extended section 22. The meandering section 20 is coupled to and extends
away from the common conductor 16. The extended section 22 is contiguous
with the meandering section 20 and extends from the end of the meandering
section 20 back towards the common conductor 16. In the illustrated
embodiment, the meandering section 20 of the first radiating arm 12 is
formed into a geometric shape known as a space-filling curve, in order to
reduce the overall size of the antenna 10. A space-filling curve is
characterized by at least ten segments which are connected in such a way
that each segment forms an angle with its adjacent segments, that is, no
pair of adjacent segments define a larger straight segment. It should be
understood, however, that the meandering section 20 may include other
space-filling curves than that shown in FIG. 1, or may optionally be
arranged in an alternative meandering geometry. FIGS. 2-6, for example,
illustrate antenna structures having meandering sections formed from
several alternative geometries. The use of shape-filling curves to form
antenna structures is described in greater detail in the co-owned PCT
Application WO 01/54225, entitled Space-Filling Miniature Antennas, which
is hereby incorporated into the present application by reference.

[0018]The second radiating arm 14 includes three linear portions. As
viewed in FIG. 1, the first linear portion extends in a vertical
direction away from the common conductor 16. The second linear portion
extends horizontally from the end of the first linear portion towards the
first radiating arm. The third linear portion extends vertically from the
end of the second linear portion in the same direction as the first
linear portion and adjacent to the meandering section 20 of the first
radiating arm 14.

[0019]As noted above, the common conductor 16 of the antenna 10 couples
the feeding port 17 to the first and second radiating arms 12, 14. The
common conductor 16 extends horizontally (as viewed in FIG. 1) beyond the
second radiating arm 14, and may be folded in a perpendicular direction
(perpendicularly into the page), as shown in FIG. 10, in order to couple
the feeding port 17 to communications circuitry in a mobile
communications device.

[0020]Operationally, the first and second radiating arms 12, 14 are each
tuned to a different frequency band, resulting in a dual-band antenna.
The antenna 10 may be tuned to the desired dual-band operating
frequencies of a mobile communications device by pre-selecting the total
conductor length of each of the radiating arms 12, 14. For example, in
the illustrated embodiment, the first radiating arm 12 may be tuned to
operate in a lower frequency band or groups of bands, such as PDC (800
MHz), CDMA (800 MHz), GSM (850 MHz), GSM (900 MHz), GPS, or some other
desired frequency band. Similarly, the second radiating arm 14 may be
tuned to operate in a higher frequency band or group of bands, such as
GPS, PDC (1500 MHz), GSM (1800 MHz), Korean PCS, CDMA/PCS (1900 MHz),
CDMA2000/UMTS, IEEE 802.11 (2.4 GHz), or some other desired frequency
band. It should be understood that, in some embodiments, the lower
frequency band of the first radiating arm 12 may overlap the higher
frequency band of the second radiating arm 14, resulting in a single
broader band. It should also be understood that the multi-band antenna 10
may be expanded to include further frequency bands by adding additional
radiating arms. For example, a third radiating arm could be added to the
antenna 10 to form a tri-band antenna.

[0021]FIG. 2 is a top view of an exemplary multi-band monopole antenna 30
including one alternative space-filling geometry. The antenna 30 show in
FIG. 2 is similar to the multi-band antenna 10 shown in FIG. 1, except
the meandering section 32 in the first radiating arm 12 includes a
different space-filling curve than that shown in FIG. 1.

[0022]FIGS. 3-9 illustrate several alternative multi-band monopole antenna
configurations 50, 70, 80, 90, 93, 95, 97. Similar to the antennas 10, 30
shown in FIGS. 1 and 2, the multi-band monopole antenna 50 illustrated in
FIG. 3 includes a common conductor 52 coupled to a first radiating arm 54
and a second radiating arm 56. The common conductor 52 includes a feeding
port 62 on a linear portion of the common conductor 52 that extends
horizontally (as viewed in FIG. 3) away from the radiating arms 54, 56,
and that may be folded in a perpendicular direction (perpendicularly into
the page) in order to couple the feeding port 62 to communications
circuitry in a mobile communications device.

[0023]The first radiating arm 54 includes a meandering section 58 and an
extended section 60. The meandering section 58 is coupled to and extends
away from the common conductor 52. The extended section 60 is contiguous
with the meandering section 58 and extends from the end of the meandering
section 58 in an arcing path back towards the common conductor 52.

[0024]The second radiating arm 56 includes three linear portions. As
viewed in FIG. 3, the first linear portion extends diagonally away from
the common conductor 52. The second linear portion extends horizontally
from the end of the first linear portion towards the first radiating arm.
The third linear portion extends vertically from the end of the second
linear portion away from the common conductor 52 and adjacent to the
meandering section 58 of the first radiating arm 54.

[0025]The multi-band monopole antennas 70, 80, 90 illustrated in FIGS. 4-6
are similar to the antenna 50 shown in FIG. 3, except each includes a
differently-patterned meandering portion 72, 82, 92 in the first
radiating arm 54. For example, the meandering portion 92 of the
multi-band antenna 90 shown in FIG. 6 meets the definition of a
space-filling curve, as described above. The meandering portions 58, 72,
82 illustrated in FIGS. 3-5, however, each include differently-shaped
periodic curves that do not meet the requirements of a space-filling
curve.

[0026]The multi-band monopole antennas 93, 95, 97 illustrated in FIGS. 7-9
are similar to the antenna 30 shown in FIG. 2, except in each of FIGS.
7-9 the expanded portion 22 of the first radiating arm 12 includes an
additional area 94, 96, 98. In FIG. 7, the expanded portion 22 of the
first radiating arm 12 includes a polygonal portion 94. In FIGS. 8 and 9,
the expanded portion 22 of the first radiating arm 12 includes a portion
96, 98 with an arcuate longitudinal edge.

[0027]FIG. 10 is a top view 100 of the exemplary multi-band monopole
antenna 10 of FIG. 1 coupled to the circuit board 102 of a mobile
communications device. The circuit board 102 includes a feeding point 104
and a ground plane 106. The ground plane 106 may, for example, be located
on one of the surfaces of the circuit board 102, or may be one layer of a
multi-layer printed circuit board. The feeding point 104 may, for
example, be a metallic bonding pad that is coupled to circuit traces 105
on one or more layers of the circuit board 102. Also illustrated, is
communication circuitry 108 that is coupled to the feeding point 104. The
communication circuitry 108 may, for example, be a multi-band transceiver
circuit that is coupled to the feeding point 104 through circuit traces
105 on the circuit board.

[0028]In order to reduce electromagnetic interference from the ground
plane 106, the antenna 10 is mounted within the mobile communications
device such that the projection of the antenna footprint on the plane of
the circuit board 102 does not intersect the metalization of the ground
plane 106 by more than fifty percent. In the illustrated embodiment 100,
the antenna 10 is mounted above the circuit board 102. That is, the
circuit board 102 is mounted in a first plane and the antenna 10 is
mounted in a second plane within the mobile communications device. In
addition, the antenna 10 is laterally offset from an edge of the circuit
board 102, such that, in this embodiment 100, the projection of the
antenna footprint on the plane of the circuit board 102 does not
intersect any of the metalization of the ground plane 106.

[0029]In order to further reduce electromagnetic interference from the
ground plane 106, the feeding point 104 is located at a position on the
circuit board 102 adjacent to a corner of the ground plane 106. The
antenna 10 is preferably coupled to the feeding point 104 by folding a
portion of the common conductor 16 perpendicularly towards the plane of
the circuit board 102 and coupling the feeding port 17 of the antenna 10
to the feeding point 104 of the circuit board 102. The feeding port 17 of
the antenna 10 may, for example, be coupled to the feeding point 104
using a commercially available connector, by bonding the feeding port 17
directly to the feeding point 104, or by some other suitable coupling
means. In other embodiments, however, the feeding port 17 of the antenna
10 may be coupled to the feeding point 104 by some means other than
folding the common conductor 16.

[0030]FIG. 11 shows an exemplary mounting structure 111 for securing a
multi-band monopole antenna 112 within a mobile communications device.
The illustrated embodiment 110 employs a multi-band monopole antenna 112
having a meandering section similar to that shown in FIG. 2. It should be
understood, however, that alternative multi-band monopole antenna
configurations, as described in FIGS. 1-9, could also be used.

[0031]The mounting structure 111 includes a flat surface 113 and at least
one protruding section 114. The antenna 112 is secured to the flat
surface 113 of the mounting structure 111, preferably using an adhesive
material. For example, the antenna 112 may be fabricated on a flex-film
substrate having a peel-type adhesive on the surface opposite the antenna
structure. Once the antenna 112 is secured to the mounting structure 111,
the mounting structure 111 is positioned in a mobile communications
device with the protruding section 114 extending over the circuit board.
The mounting structure 111 and antenna 112 may then be secured to the
circuit board and to the housing of the mobile communications device
using one or more apertures 116, 117 within the mounting structure 111.

[0032]FIG. 12 is an exploded view of an exemplary clamshell-type cellular
telephone 120 having a multi-band monopole antenna 121. The cellular
telephone 120 includes a lower circuit board 122, an upper circuit board
124, and the multi-band antenna 121 secured to a mounting structure 110.
Also illustrated are an upper and a lower housing 128, 130 that join to
enclose the circuit boards 122, 124 and antenna 121. The illustrated
multi-band monopole antenna 121 is similar to the multi-band antenna 30
shown in FIG. 2. It should be understood, however, that alternative
antenna configurations, as described above with reference to FIGS. 1-9,
could also be used.

[0033]The lower circuit board 122 is similar to the circuit board 102
described above with reference to FIG. 10, and includes a ground plane
106, a feeding point 104, and communications circuitry 108. The
multi-band antenna 121 is secured to a mounting structure 110 and coupled
to the lower circuit board 122, as described above with reference to
FIGS. 10 and 11. The lower circuit board 122 is then connected to the
upper circuit board 124 with a hinge 126, enabling the upper and lower
circuit boards 122, 124 to be folded together in a manner typical for
clamshell-type cellular phones. In order to further reduce
electromagnetic interference from the upper and lower circuit boards 122,
124, the multi-band antenna 121 is preferably mounted on the lower
circuit board 122 adjacent to the hinge 126.

[0034]FIG. 13 is an exploded view of an exemplary candy-bar-type cellular
telephone 200 having a multi-band monopole antenna 201. The cellular
telephone 200 includes the multi-band monopole antenna 201 secured to a
mounting structure 110, a circuit board 214, and an upper and lower
housing 220, 222. The circuit board 214 is similar to the circuit board
102 described above with reference to FIG. 10, and includes a ground
plane 106, a feeding point 104, and communications circuitry 108. The
illustrated antenna 201 is similar to the multi-band monopole antenna
shown in FIG. 3, however alternative antenna configurations, as described
above with reference to FIGS. 1-9, could also be used.

[0035]The multi-band antenna 201 is secured to the mounting structure 110
and coupled to the circuit board 214 as described above with reference to
FIGS. 10 and 11. The upper and lower housings 220, 222 are then joined to
enclose the antenna 212 and circuit board 214.

[0036]FIG. 14 is an exploded view of an exemplary personal digital
assistant (PDA) 230 having a multi-band monopole antenna 231. The PDA 230
includes the multi-band monopole antenna 231 secured to a mounting
structure 110, a circuit board 236, and an upper and lower housing 242,
244. Although shaped differently, the PDA circuit board 236 is similar to
the circuit board 102 described above with reference to FIG. 10, and
includes a ground plane 106, a feeding point 104, and communications
circuitry 108. The illustrated antenna 231 is similar to the multi-band
monopole antenna shown in FIG. 5, however alternative antenna
configurations, as described above with reference to FIGS. 1-9, could
also be used.

[0037]The multi-band antenna 231 is secured to the mounting structure 110
and coupled to the circuit board 214 as described above with reference to
FIGS. 10 and 11. In slight contrast to FIG. 10, however, the PDA circuit
board 236 defines an L-shaped slot along an edge of the circuit board 236
into which the antenna 231 and mounting structure 110 are secured in
order to conserve space within the PDA 230. The upper and lower housings
242, 244 are then joined together to enclose the antenna 231 and circuit
board 236.

[0038]This written description uses examples to disclose the invention,
including the best mode, and also to enable any person skilled in the art
to make and use the invention. The patentable scope of the invention is
defined by the claims, and may include other examples that occur to those
skilled in the art.